Both ionization-type and photoelectric-type smoke detectors are known and have proved to be useful in providing warnings of the existence of fire. It is well known that the two types of detectors are sensitive to different types of smoke.
Ionization-type detectors respond rapidly to flaming fires. Photoelectric-type detectors respond rapidly to smoldering fires.
There has been a continuing interest in combining such sensors into a single housing so as to obtain the advantages of both types of detectors in a single unit. In this regard, it is desirable to be able to provide the smallest possible internal volume in the photoelectric-type detector so as to minimize the overall size of the detector.
It is also known to be desirable to minimize reflections within the internal volume of photoelectric-type detectors so as to minimize background noise. Thus, there continues to be a need for combination ionization-type and photoelectric-type smoke detectors which can be manufactured with minimal volumes. Further, it would be desirable to create a structure for a combination detector wherein reflections within the volume of the housing which includes the two types of detectors are minimized.